Early Career winner uses supercomputers to probe mysteries of the universe

A boyhood fascination with philosophy and nature put Gaute Hagen on the path he still follows at Oak Ridge National Laboratory: seeking answers to some of life’s most basic questions. By asking the right ones, the native of Norway hopes for insights that could rewrite physics textbooks.

Hagen received an Early Career Research award from the Department of Energy Office of Science in 2013, but he wasn’t all that interested in physics and math when he graduated from high school. After earning a bachelor’s degree in philosophy, he discovered that to pursue a more mature approach to solving some of nature’s riddles he would have to bolster his resume in math and the hard sciences. He did that by earning a master’s degree and doctorate in theoretical physics from the University of Bergen in Norway in 2005.

Now, instead of pondering the teachings of Aristotle, Descartes, Fichte and Hobbes, Hagen probes the composition of matter. His world consists of neutrons, protons, quarks and gluons. And supercomputing. Without the exponential growth in computing power enjoyed by ORNL’s Jaguar and, now, Titan, many recent discoveries would not have been possible.

“Experimental observations can reveal new and exciting phenomena at work in the formation of the elements in the universe,” Hagen said. “However, only a working model of the underlying forces involved can provide a proper understanding of the underlying physics. Thanks to sophisticated mathematical methods and algorithms -- and the power of supercomputers -- nuclear physicists have unveiled some of the fundamental interactions of the strange and rare isotopes not found on Earth.”

Hagen’s focus is on learning how matter is built from smaller building blocks and defining interactions.

“We are trying to map out the chart of atomic nuclei and understand exotic matter that can be observed in laboratories and those that exist in supernova,” Hagen said. “Our hope is that this knowledge will help us discover how the matter that we see around us on a daily basis came to be from the smallest building blocks in the early stages of the universe.”

Hagen has published 49 refereed articles and conference proceedings and presented more than 70 invited talks since earning his doctorate in 2005. He joined the ORNL Physics Division in 2008 and scored a major success with a paper published in Physical Review Letters in July 2012. He is especially proud of that paper, which provides insight into the neutron-rich isotopes of calcium. The work finally put to rest a theory that calcium-54 is what’s called “magic,” or one that is exceptionally stable.

“Whether calcium-54 is magic had been an open question,” Hagen said. “However, recent investigations of nuclei far away from the valley of stability reveal new and surprising features that challenge the traditional shell model.”

Hagen and colleagues theorized that very neutron-rich calcium isotopes – those with a neutron-to-proton ratio of close to 2:1 – do not follow the classic rules of the shell model. Their first principles predictions were verified in the fall of 2012 at the RIKEN natural sciences institute in Japan. “Our prediction turned out to be right on the spot,” Hagen said.

“Due to an intricate interplay between the very weakly bound outermost neutrons and three nucleon forces, the traditional shell structure melts away and rearranges itself in a new and unexpected way,” Hagen said.

This is a big deal to physicists who for decades have studied nuclear shell models, which examine the relationships of protons and neutrons to a nucleus. For Hagen and fellow physicists who seek answers to the origin of life and other mysteries, more questions pop up for every one they answer. For Hagen, that’s what makes coming to work every day exciting.

The DOE Early Career Research award program is designed to bolster the nation’s workforce by providing support to exceptional researchers during their crucial first years when many scientists do their most formative work. – Ron Walli, Feb. 25, 2014